Class ELProcessor

java.lang.Object
jakarta.el.ELProcessor
public class ELProcessor extends Object
Provides a simple API for evaluating EL expressions in a standalone environment. This class wraps an ELManager and provides methods for evaluating expressions, defining beans and functions, and managing variables. It is the primary entry point for applications that use the EL API outside of a Jakarta EE container.
Since:
EL 3.0

  • Constructor Details

    • ELProcessor

      public ELProcessor()
      Constructs an ELProcessor with a default ELManager and StandardELContext. The processor is ready to evaluate expressions immediately after construction.

  • Method Details

    • getELManager

      public ELManager getELManager()
      Returns the ELManager that manages the EL context, resolvers, functions, and variables for this processor.
      Returns:
      the ELManager instance

    • eval

      public <T> T eval(String expression)
      Evaluates the given EL expression and returns the result as the requested type. The expression is automatically wrapped in ${} delimiters before evaluation.
      Type Parameters:
      T - the expected result type
      Parameters:
      expression - the EL expression to evaluate
      Returns:
      the result of evaluating the expression, coerced to the requested type
      Throws:
      ELException - if the expression cannot be evaluated

    • getValue

      public <T> T getValue(String expression, Class<T> expectedType)
      Evaluates the given EL expression and returns the result coerced to the expected type. The expression is automatically wrapped in ${} delimiters before evaluation.
      Type Parameters:
      T - the expected result type
      Parameters:
      expression - the EL expression to evaluate
      expectedType - the class of the expected result type
      Returns:
      the result of evaluating the expression, coerced to the expected type
      Throws:
      ELException - if the expression cannot be evaluated

    • setValue

      public void setValue(String expression, Object value)
      Evaluates the given EL expression and sets the result to the specified value. This is used for EL assignment expressions. The expression is automatically wrapped in ${} delimiters before evaluation.
      Parameters:
      expression - the EL expression to evaluate
      value - the value to assign
      Throws:
      ELException - if the expression cannot be evaluated or the target is not writable

    • setVariable

      public void setVariable(String variable, String expression)
      Registers a variable in the EL context. The variable is associated with the result of evaluating the given expression. Passing a null expression removes the variable from the context.
      Parameters:
      variable - the variable name
      expression - the EL expression to associate with the variable, or null to remove
      Throws:
      ELException - if the expression cannot be evaluated

    • defineFunction

      public void defineFunction(String prefix, String function, String className, String methodName) throws ClassNotFoundException, NoSuchMethodException
      Registers a function in the EL context by looking up the static method in the given class. The method name may include a return type and parameter signature in the format returnType methodName(paramTypes). The function is then callable in EL expressions as prefix:function(args).
      Parameters:
      prefix - the namespace prefix for the function
      function - the local function name, or empty to use the method name
      className - the fully qualified name of the class containing the static method
      methodName - the method name, optionally with return type and parameter signature
      Throws:
      ClassNotFoundException - if the class cannot be found or is not public
      NoSuchMethodException - if the method cannot be found or is not a public static method

    • defineFunction

      public void defineFunction(String prefix, String function, Method method) throws NoSuchMethodException
      Map a method to a function name.
      Parameters:
      prefix - Function prefix
      function - Function name
      method - Method
      Throws:
      NullPointerException - If any of the arguments are null
      NoSuchMethodException - If the method is not static

    • defineBean

      public void defineBean(String name, Object bean)
      Defines or removes a bean accessible by name in EL expressions. When a non-null bean is provided, it is stored under the given name. When null is provided, the bean with the given name is removed.
      Parameters:
      name - the bean name
      bean - the bean object to define, or null to remove the bean